The present disclosure relates generally an integrated circuit device and, more particularly, a gate structure of a semiconductor device.
As technology nodes decrease, semiconductor fabrication processes have introduced the use of gate dielectric materials having a high dielectric constant (e.g., high-k dielectrics). The high-k dielectrics exhibit a higher dielectric constant than the traditionally used silicon dioxide, which allows for thicker dielectric layers to be used to obtain similar equivalent oxide thicknesses (EOTs). The processes also benefit from the introduction of metal gate structures providing a lower resistance than the traditional polysilicon gate structures.
In particular as gate lengths decrease, minimization of equivalent oxide thickness (EOT) becomes more critical. However, an interfacial layer may be required between the gate dielectric layer (e.g., HfO2) and the silicon substrate. The interfacial layer also contributes to the EOT of the gate structure. Therefore, as the scale of gate lengths decrease, the thickness of the interfacial layer becomes more critical. It is also desirable to increase the dielectric constant of the gate dielectric to control the EOT of the gate structure. Further, it is desirable to cure oxygen vacancies in the gate dielectric layer.
Therefore, what is needed is an improved gate structure and fabrication method.